Optical electronics are used many consumer electronics products, such as digital cameras, fax machines, scanners, security and surveillance cameras, personal computer (PC) cameras, camcorders, mobile phones, personal digital assistants (PDAs) and toys, as examples. Some optical electronics utilize image sensors that are fabricated on a semiconductor substrate, with logic circuitry and support circuitry being formed on the same substrate. For example, one such integrated image sensor device is a complementary metal oxide semiconductor (CMOS) image sensor. Integrated image sensor devices usually comprise an array of sensors formed proximate digital integrated circuit devices which may include logic circuits, transistors, and other active components.
A problem with image sensors formed on the same semiconductor substrate as logic and other circuitry is that several layers of dielectric material are deposited over the image sensor. The dielectric material layers decrease the sensitivity of the sensor, resulting in a decrease in the amount of light or energy sensed by the sensor, which degrades the sensitivity of the sensor.
Therefore, what is needed in the art is an improved CMOS image sensor design and method of fabrication thereof that results in increased sensitivity of the sensor.